442 



AMERICAN FORESTRY 



7 rain gages and 30 snow gages and the 

 engineers visited these continually dur- 

 ing the winter on snowshoes, the snow 

 being from 4 to 7 feet deep ; in the ad- 

 joining Burnt Brook basin (the de- 

 forested area) it established 9 rain 

 gages and 18 snow gages. On both 

 streams hydrometric stations were es- 

 tablished and the stream flow deter- 

 mined with a high degree of accuracy. 

 The Survey report shows that the max- 

 imum flood flow from the forested 

 basin was only 67 per cent of that from 

 the deforested basin. 



During the period of these storms 

 Burnt Brook (deforested) contributed 

 a much greater volume of water to 

 Pemigewasset River than did Shoal 

 Pond Brook (forested). "The stream of 

 the forested basin is observed to be the 

 steadier of the two and in proportion 

 to its drainage area it tends — at least 

 during the spring months — to promote 

 a steady flow of water in the master 

 stream of which it is a tributary." 



The conclusions of Director George 

 Otis Smith, of the Survey, are as fol- 

 lows : 



"The comparison between two ad- 

 jacent basins during critical periods is 

 presented in this preliminary statement 

 as a sufficient showing for the purposes 

 of the National Forest Reservation 

 Commission. While data covering 

 longer periods for both these and other 

 basins in the White Mountains have 

 been collected and will be available for 

 the more complete report, the particu- 

 lar case of the Burnt Brook and Shoal 

 Pond Brook basins is typical for the 

 region and establishes the general con- 

 clusion that a direct relation exists be- 

 tween forest cover and stream regula- 

 tion. 



"The results of the Burnt Brook- 

 Shoal Pond Brook studies are held to 

 show that throughout the White Moun- 

 tains the removal of forest growth 

 must be expected to decrease the nat- 

 ural steadiness of dependent streams 

 during the spring months at least. 



"The foregoing conclusion forms a 

 strong basis for arguing the desirabil- 

 ity of painstaking methods of admin- 

 istration in respect to forest lands in 

 the White Mountain region. Defores- 



tation followed by fires, as in the Burnt 

 Brook basin, results in conditions un- 

 favorable to natural spring storage be- 

 cause conducive to rapid snow melt- 

 ing and stream run-oft". Control of 

 White Alountain lands that would re- 

 duce fires to a minimum and promote 

 normal reforstation must result in a 

 great improvement over present ten- 

 dencies, and this improvement in forest 

 cover can logically be expected to fav- 

 orably aft'ect stream regulation to the 

 extent quantitatively indicated in the 

 comparison of the forested Shoal Pond 

 Brook with the deforested Burnt 

 Brook. 



"While the intensive hydrometric 

 work was confined to a few headwater 

 tributaries of the Connecticut and Mer- 

 rimac rivers, the basins studied were 

 selected as typical for the whole White 

 Mountain area, and the field examina- 

 tions over this region have shown the 

 tracts now under consideration for pur- 

 chase to be similar to the basins here 

 reported upon. Therefore, the favor- 

 able showing of this report is of gen- 

 eral application in the White Moun- 

 tain area." 



Such an actual demonstration and 

 quantitative measure of the perform- 

 ance of different areas, some forested 

 and others deforested, has never been 

 attempted in trying to determine the 

 effect of forest cover on stream flow. 

 Efforts to arrive at definite conclusions 

 have always been based on a study of 

 long-time records of precipitation and 

 stream discharge ; but owing to the 

 many qualifying factors, such efforts 

 have simply resulted in divergent opin- 

 ions and inconclusive controversies. 

 The results of the present actual meas- 

 urements in these mimic drainage 

 basins, so accurate and refined in 

 method as to approach laboratory ex- 

 periments, where exact results may be 

 expected, leave no doubt as to the con- 

 clusion. Forest cover and the resulting 

 forest mat in the White Mountain 

 granite area does, to a considerable and 

 measurable degree, steady and regulate 

 stream flow, and therefore must be 

 stated as an important factor in main- 

 taining the navigability of streams 

 whose headwaters lie in such areas. 



